Brachial plexus is one of the tough topic to remember by anyone undergoing MBBS course. This slide gives you in detail about the Origin / Course / Formation / Distribution / Anatomical variations & Applied anatomy & Made so easy to Remember & Draw as well.
2. Contents of Discussion
Spinal Nerves
Nerve Plexus
BP – Origin & Relations
Formation
Parts of BP
Distribution - Nerve Supply – areas
Anatomical Variations
Applied Anatomy
3. Spinal Nerves Spinal nerves attach to the
spinal cord via roots
Dorsal root
Has only sensory neurons
Attached to cord via rootlets
Dorsal root ganglion
Ventral root
Has only motor neurons
No ganglion - all cell bodies
of motor neurons found in
gray matter of spinal cord
4. Spinal Nerves
31 pair
each contains thousands of nerve fibers
All are mixed nerves have both sensory and motor
neurons
Connect to the spinal cord
Exit from SC – Supplying the muscles & structures
of the body
5. 8 pairs of cervical nerves from
C1 to C8
12 pairs of thoracic nerves
from T1-T12
5 pairs of lumbar nerves from
L1 to L5
5 pairs of sacral nerves from
S1 to S5
1 pair of coccygeal nerves
located at C zero (Co)
Spinal Nerves
6. 12-6
Formation of Rami
Rami are lateral branches of a
spinal nerve
Rami contain both sensory and
motor neurons
Two major groups
Dorsal ramus
Neurons innervate the
dorsal regions of the
body
Ventral ramus
Larger
Neurons innervate the
ventral regions of the
body
Braid together to form
plexuses (plexi)
7. 12-7
Nerve Plexuses
Nerve plexus
A nerve plexus is nothing more than a
system or network of connected nerve
fibers that link spinal nerves with specific
areas of the body . A network of ventral
rami.
Ventral rami (except T2-T12)
Branch and join with one another
Form nerve plexuses
In cervical, brachial, lumbar, and sacral regions
No plexus formed in thoracic region of s.c.
8. 12-8
Branches
of
Spinal
Nerves
Dorsal Ramus
Neurons within muscles of trunk and back
Ventral Ramus (VR)
Braid together to form plexuses
Cervical plexus - VR of C1-C4
Brachial plexus - VR of C5-T1
Lumbar plexus - VR of L1-L4
Sacral plexus - VR of L4-S4
Coccygeal plexus -VR of S4&S5
Communicating Rami: communicate
with sympathetic chain of ganglia
Covered in ANS unit
9. 12-9
Brachial Plexus - Origin
Formed by ventral rami of spinal
nerves C5-T1
Five ventral rami form
Roots / Trunks that separate into
Divisions that then form
Cords that give rise to Branches
Major nerves
Axillary
Radial
Musculocutaneous
Ulnar
Median
10. Brachial Plexus
15 cms long ,spinal column to
axilla.
Brachial plexus is responsible for
cutaneous (sensory) and
muscular (motor) innervation of
the entire upper limb & pectoral
girdle.
It proceeds through the neck, the
axilla and into the arm.
11.
12. In the neck, the brachial plexus
lies in the posterior triangle,
being covered by the skin,
Platysma, and deep fascia; where
it is crossed by the
supraclavicular nerves, the
inferior belly of the Omohyoid,
the external jugular vein, and the
transverse cervical artery.
Relations - BP
13. Relations - BP
When it emerges
between the Scalene
anterior and medius
--* its upper part lies
above the third part of
the subclavian artery,
* while the trunk
formed by the union of
C8 & T1 is placed
behind the artery.
14. The plexus next passes behind the clavicle,
the Subclavius, and the transverse scapular
vessels, and lies upon the first digitation of the
Serratus anterior, and the Subscapularis.
Relations - BP
15. Relations
In the axilla it is placed
lateral to the first portion
of the axillary artery; it
surrounds the second part
of the artery, one cord
lying medial to it, one
lateral to it, and one
behind it; at the lower part
of the axilla it gives off its
terminal branches to the
upper limb.
18. ROOTS
Originates froms C5-C8 and most of T1
Receives gray rami communicates from the
symphathetic trunk.
Carry postganglionic symphathetic fibers
onto root for distribution of periphery.
Root and trunk enter posterior triangle of
neck by passing between anterior scalene
and middle scalene muscles and lies
between superior and posterior to subclavian
artery.
19. TRUNKS
C5,C6 roots pass down wards between
Scalenus medius and Scalenus anterior
muscles and unite to form SUPERIOR
TRUNK
C7 root pass between Scalenus muscles and
at laeral border of scalenus anterior emreges
as MIDDLE TRUNK
C8, T1 roots unite behind a fascial sheet
(sibson”s fascia) and beneath the subclavian
artery form LOWER TRUNK
20. DIVISION
Lateral to the 1st
rib , where three trunks are
located behind the axillary artery ,they separate
into 3 anterior and 3 posterior divisions
The 3 anterior division form parts of brachial
plexus that ultimately give rise to peripheral
nerves associated with the anterior compartment
of arm or forearm.
The 3 posterior division combine to form parts of
the brachial plexus that give rise to nerves
associated with the posterior compartments.
21. CORDS
3 posterior divisions unite to form
posterior cord
Anterior divisions of upper and ,middle
trunks (C5-C7) unite to form lateral cord
Anterior division of lower trunk forms
medial cord(C8-T1)
Cords – named after their relation with AA
& passes through the thoracic outlet and
give off major branches
22. BRANCHES - Roots
From the Roots
Dorsal Scapular nerve
Derived from C5 root
Motor nerve to the
Rhomboideus major and
minor muscles
23. Roots
Long Thoracic nerve
Derived from C 5,6,7
Innervates the serratus
anterior muscle
26. Lateral Cord
Direct branches:
Lateral pectoral nerve: C5-7
To clavicular head of pectoralis
major muscle
Terminal nerves:
Musculocutaneous: C5-7
Lateral root of median
nerve: C5-7
27.
28. Medial Cord: Direct Branches
Medial pectoral nerve:
C8-T1
To sternal head of pectoralis
major muscle and pectoralis
minor muscle.
Medial cutaneous nerve to
arm
Medial cutaneous nerve to
forearm
36. Posterior Cord Terminal Nerves
Radial nerve: C5-T1
Motor:
Posterior compartments of
arm and forearm.
Brachioradialis muscle
Sensory:
Back of arm, forearm, hand
40. Anatomic Variations
The plexus may include anterior rami from C4
or T2 and these are designated as
Pre fixed- C4 added
Post fixed- T2 added.
The connective tissue sheath that invests the
plexus especially in the axillary region has a
convoluted and septated structure that can
lead to non uniform distribution of local
anaesthetics .
41. The musculocutaneous nerve may fuse to or have
communications with the median nerve , which
can result in its absence from within the
coracobrachialis muscle.
Communication between median and ulnar nerves
is common in the forearm with the median nerve
replacing the innervations to various muscles
normally supplied by the ulnar nerve.
Variations with respect to vessels within the arm
may be present like double axillary veins , high
origin of radial artery and double brachial arteries.
42. The interscalene groove may have variations
in the relationship between the plexus roots
and trunks and the muscles.
For eg.- the C5 or C6 roots may traverse
through or anterior to the anterior scalene
muscles.
In many specimens no inferior trunk exists , a
single cord or a pair of cords may develop. In
some cases no discrete posterior cord forms ,
with the posterior divisions diverging to form
terminal branches.
44. Brachial Plexus Injury
Obstetric palsy - Injury to all or portion of a child
brachial plexus occurring at that time of the
delivery.
Excessive lateral traction on the head so that the
head is pulled away from the shoulder.
Divide into :
Erb’s Duchenne Palsy
Klumpkee’s Palsy
45.
46.
47. Erb’sparalysis
•C5 -C6
•Birth injury / Trauma
•Arm hangs by the side
+ Rotate medially
•Forearm pronated +
extended
•Flexed wrist + fingers
•Deltoid/supraspinatus/
infraspinatus/biceps/
brachialis
. LOS – in arm
50. Klumpke’sparalysis
•C8 –T1
•Traction injuries / Fall
* Intrinsic muscles of the hand +
long flexors of the wrist & hand
paralysed
• Claw hand = extension at MPJ +
flexion at IPJ ( wrist & hand )
* Forearm – supinated
* LOS – medial side - am
•Cervical rib can cause paralysis
similar to Klumpke’sparalysis with
post-fixed T2 contribution
58. “3M” comes off the medial cord.
Axillary Radial
Roots
Trunks
Divisions
Cords
Branches
C5 C6 C7 C8 T1
Upper Middle Lower
Musculocutaneous Median Ulnar
Lateral
Posterior
Medial
Upper subscapular
Lower subscapular
Thoracodorsal
Medial pectoral n.
Medial cutan. n. of arm
Medial cutan. n. forearm
SLOWSLOW
59. The lateral pectoral n. comes off the lateral cord.
Axillary Radial
Roots
Trunks
Divisions
Cords
Branches
C5 C6 C7 C8 T1
Upper Middle Lower
Musculocutaneous Median Ulnar
Lateral
Posterior
Medial
Upper subscapular
Lower subscapular
Thoracodorsal
Medial pectoral n.
Medial cutan. n. of arm
Medial cutan. n. forearm
Lateral pectoral n.
60. There are 4 supraclavicular branches.
Axillary Radial
Roots
Trunks
Divisions
Cords
Branches
C5 C6 C7 C8 T1
Upper Middle Lower
Musculocutaneous Median Ulnar
Lateral
Posterior
Medial
Upper subscapular
Lower subscapular
Thoracodorsal
Medial pectoral n.
Medial cutan. n. of arm
Medial cutan. n. forearm
Lateral pectoral n.
Dorsal Scapular n.
N. to subclavius
Suprascapular n.
Long
Thoracic n.
SLOW
61. That’s it! The Brachial Plexus
Axillary Radial
Roots
Trunks
Divisions
Cords
Branches
C5 C6 C7 C8 T1
Upper Middle Lower
Musculocutaneous Median Ulnar
Lateral
Posterior
Medial
Upper subscapular
Lower subscapular
Thoracodorsal
Medial pectoral n.
Medial cutan. n. of arm
Medial cutan. n. forearm
Lateral pectoral n.
Dorsal Scapular n.
N. to subclavius
Suprascapular n.
Long
Thoracic n.